Add export tests.

testing/cmake/test_export/test_bench.cu

@@ -0,0 +1,13 @@
+#include <nvbench/nvbench.cuh>
+
+// Grab some testing kernels from NVBench:
+#include <nvbench/test_kernels.cuh>
+
+void simple(nvbench::state &state)
+{
+  state.exec([](nvbench::launch &launch) {
+    // Sleep for 1 millisecond:
+    nvbench::sleep_kernel<<<1, 1, 0, launch.get_stream()>>>(1e-3);
+  });
+}
+NVBENCH_BENCH(simple);